• 19.9 baseline — 0.6 × season 19.8 (12 gm) + 0.4 × last 10 20.2
• +0.9 opponent leak — they concede 386.2/game vs a 369 league average
• −2.3 at this ground — averages 17.7 there (6 gm)
• vs them: averages 20.0 over 1 game — evidence, never summed

Derived, not measured — plain arithmetic over his real games, shown in full. Adjustments can overlap (a game at this ground can also be a wet one); they add simply, and this note is the admission. Round 7: 31 — far outside his usual range; kept in the average, not smoothed away.